Bellows

ABSTRACT

A method and apparatus for forming convolutions in a tube, the method including the steps of arranging a single roller to bear against one wall of the tube and pair of rollers to bear against the other wall of the tube, rotating the tube, moving the axes of the single roller and pair of rollers towards each other and simultaneously moving two of the rollers towards each other and simultaneously moving two of the rollers along their axis or axes towards the third roller whereby a convolution is formed in one operation in the wall of the tube as said tube is rotated.

United States Patent I l l [56] References Cited UNITED STATES PATENTS 3,435,651 4/1969 Mclnnis 29/454 Primary Examiner-Lowell A Larson At!0rneyNorris and Bateman ABSTRACT: A method and apparatus for forming convolutions in a tube, the method including the steps of arranging a single roller to bear against one wall of the tube and pair of rollers to bear against the other wall of the tube, rotating the tube, moving the axes of the single roller and pair of rollers towards each other and simultaneously moving two of the re]- lers towards each other and simultaneously moving two of the rollers along their axis or axes towards the third roller whereby a convolution is formed in one operation in the wall of the tube as said tube is rotated.

PATENTED JUL2 7:971

INVENTOR GORDON CHARLES HOLT BELLOWS This invention relates to bellows and is particularly concerned with a method and apparatus for forming convolutions in a tube so as to form a tubular bellows.

Tubular bellows are formed according to one method by mounting a tube between coldforming rollers. A single roller is arranged to bear against the inner surface of the tube and a pair of rollers are arranged to bear against the outer surface of the tube. The rollers and tube are rotated and the inner roller is progressively moved radially outwards. The movement of the inner roller causes the region of the tube wall against which said roller bears to move outwardly therewith and the two outer rollers are arranged so as to limit the extent of the said region of the tube wall. in this way a convolution is formed in the tube wall.

However, it is not possible with known arrangements to form a complete convolution in one operation. After the first set of rollers have formed a slight indentation in the tube wall they must be replaced by rollers having a more sharply tapered edge and which are arranged to be closer together. Sometimes as many as four sets of rollers are required before a complete convolution can be formed in the wall of the tube. This is because the thickness of the tube material must of necessity be thin toallow deformation of the tube wall to form convolutions and because it is so thin the rollers must at first be spaced wide apart in order to prevent the tube wall from buckling radially inwardly when the inner roller is moved outwards.

The present invention aims to provide a method and apparatus for forming convolutions in a tube in one operation using only a single set of rollers.

According to the present invention, there is provided a method of forming convolutions in a tube, which method comprises arranging a single roller to bear against one wall of the tube and a pair of rollers to bear against the other wall of the tube, rotating the tube, moving the axes of the single roller and pair of rollers towards each other and simultaneously moving two of the rollers along their axis or axes towards the third roller whereby a convolution is formed in one operation in the wall of the tube as said tube is rotated.

Preferably, the single roller is arranged to bear against the inner wall of the tube and the pair of rollers arranged to bear against the outer wall of the tube.

The invention also extends to apparatus for performing the method according to the invention, said apparatus comprising a single roller mounted on a first spindle and a pair of rollers mounted on a second spindle, means for rotating a tube in which a convolution is to be formed, means for moving at least one of the spindles laterally towards the other spindle when the tube is rotating, and means for moving two of the rollers axially towards the third roller.

The tube may be driven by the rollers which are themselves driven by a suitable drive means and which bear against the wall of the tube. Preferably, however, the tube itself is driven by suitable drive means and the rollers are free rolling and driven by virtue of their engagement with the walls of the tube.

The invention further extends to a tubular bellows when made by the method or with the apparatus according to the invention.

The invention will now be further described, by way of example, with reference to the accompanying drawing which is a side elevation of one embodiment of an apparatus according to the invention showing part ofa tube therein.

Referring to the drawing, the apparatus comprises a single inner roller I mounted on a spindle 2 and arranged to bear against the inner wall of a tube 3. The spindle 2 is received in bearings 4 in a machine tool post 5 which is mounted for both axial and lateral movement on suitable means (not shown).

A pair of rollers 6,7 are mounted on a second spindle 8 and the roller 6 is secured to the spindle by a key 9 and setscrew 10. The roller 7 is freely mounted on the spindle and can slide with respect thereto. The roller 7 normally, however, rests on a sleeve 11 mounted in a bearing 13 in a housing B2. The spindle is slidably mounted in the sleeve 11 and in a second bearing 14 in the housing 12. The spindle 8 is provided with means (not shown) for displacing said spindle and the roller 6 axially. The housing 12 is mounted on a number of guide pins 15 which are connected to a machine tool-post 16. The machine toolpost 16 is slidably mounted on a guide 17 provided in the base member 18 and is connected to a ram 19 by a rod 20. The ram is capable of moving the machine toolpost l6 and hence the housing 12 in a vertical direction as shown in the drawing.

The operation of the apparatus according to the invention will now be described in detail. A tube in which convolutions are to be formed is secured to a machine bed 21 by suitable means such as the clamp 22 shown in the drawing. The bed 21 is connected to suitable drive means (not shown) for rotating the tube when required.

When the tube has been secured to the machine bed, the machine toolpost 5 is displaced vertically until the roller 1 faces the point of the tube at which a convolution is desired. The toolpost 5 is then moved towards the tube until the roller 1 bears against the inner wall of the tube.

The machine toolpost 16 is moved along the guide 17 until the rollers 6,7 are substantially opposite roller 1 and the housing 12 is then moved along the guide pins 15 until the rollers 6 and 7 bear against the outer wall of the tube. In this position the roller 6 is a short distance above, and the roller 7 an equal distance below, the roller 1.

The tube 3 is now rotated and the inner and outer rollers are rotated, by virtue of their engagement with the tube walls, in opposite directions. As the tube is rotated, the machine toolpost 5 and hence the roller 1 is moved laterally towards the rollers 6 and 7. The area of tube wall between the rollers 6 and 7 is therefore deformed radially outwardly. At the same time, the machine toolpost S is moved downwardly so that the vertical distance between rollers l and 7 is decreased. Spindle 8 is also moved downwardly but at twice the speed of the machine toolpost 5 so that the vertical distance between rollers l and 6 decreases by the same amount as that between rollers l and 7. The roller 7 does not of course move vertically during this convolution forming operation but remains seated on the sleeve 1]. In this way a convolution is formed in a tube in one operation with only one set of forming rollers, no pregrooving of the tube being necessary.

After forming one convolution in a tube, the rollers may be moved away from the tube walls and the machine toolposts displaced vertically to form a second convolution in said tube. Thus a tubular bellows having a series of convolutions may easily be formed by the method and with the apparatus according to the present invention.

It will be appreciated that although the drawing shows the apparatus with the spindles extending in! a vertical direction, the apparatus may, if desired, be so arranged that the spindles and associated components extend horizontally.

Further, according to an alternative embodiment, during forming of a convolution in a tube, the two outer spindles are moved axially towards each other while the inner spindle remains axially stationary.

The apparatus according to the present invention is particularly suitable for use in conjunction with the apparatus which forms the subject of our copending application No. 795,149 filed Jan. 30, 1969, but it will be appreciated that this apparatus may be used in any apparatus using rollers for forming convolutions in tubes.

The apparatus above described will provide a bellows in which all of the convolutions extend substantially radially outwards with respect to the tube. However if it is desired to produce convolutions which extend radially inwardly, the inner spindle will be fixed laterally and the outer spindle will be moved laterally towards said inner spindle. If both radially inwardly and outwardly convolutions are: desired, both of the spindles will be arranged for lateral movement during forming of the convolutions.

Although the drawing shows a tube having only a single layer or ply it is possible, using the apparatus according to the invention, to form convolutions in multiply tubes.

lclaim:

l. A method of forming convolutions in a tube, which method comprises arranging a freely rotatable single forming roller to bear against one wall of the tube and a pair of freely rotatable forming rollers to bear against the other wall of the tube, positively rotating the tube about its longitudinal axis, moving the axis of the single roller and pair of rollers towards each other and simultaneously moving two of the rollers along their axis or axes towards the third roller whereby a convolution is formed in one operation in the wall of the tube as said tube is rotated.

2. A method as claimed in claim I, wherein the single roller is arranged to bear against the inner wall of the tube and the pair of rollers are arranged to bear against the outer wall of the tube.

3. The method defined in claim I, wherein said single roller engages the inner periphery of said tube and said pair of rollers are axially spaced and engage the outer periphery of said tube one at each side of said single roller, said inner roller is displaced axially of the tube toward one of said outer rollers, and the other of said outer rollers is displaced in said direction at a faster rate.

4. Apparatus for forming convolutions in a tube comprising rotatable means for mounting one end of a tube, said means being rotatable about the longitudinal axis of said tube, a single inner roller mounted on a first axis for peripheral engage ment with the inner surface of said tube, two axially spaced outer rollers mounted on a second axis for peripheral engagement with the outer surface of said tube, said inner roller engaging the tube in a region between said outer rollers, and said spindle axes being parallel to the axis of rotation of the tube, and means for moving the inner roller substantially radially outwardly with respect to the rotating tube and axially toward one of said outer rollers while at the same time axially displacing the other of said outer rollers in the same direction.

5. The apparatus defined in claim 4, wherein said other outer roller is displaced at a faster rate than said inner roller.

6. The apparatus defined in claim 5 wherein said other outer roller is displaced at substantially twice the rate as said inner roller.

7. Apparatus as defined in claim 4, wherein said rollers are all mounted for free rotation about their respective axes.

8. The apparatus defined in claim 4, wherein said outer rollers are mounted on a common spindle, one of said outer rollers being axially slidable on said spindle and the other of said outer rollers being fixed on said spindle.

9. The apparatus defined in claim 8, wherein said spindle is mounted for rotation and axial displacement.

10. The apparatus defined in claim 9, wherein said spindle is carried by a member that is mounted for displacement axially and radially of said tube.

11. The apparatus defined in claim 4, wherein said inner roller is mounted on a spindlejournaled in a machine post that is movable both radially and axially of said tube.

12. The apparatus defined in claim 4, wherein said tube mounting means is rotatable about a substantially vertical axis and means is provided thereon for clamping the lower end of said tube to fix the tube coaxially with said axis, the upper end of said tube being axially free. 

1. A method of forming convolutions in a tube, which method comprises arranging a freely rotatable single forming roller to bear against one wall of the tube and a pair of freely rotatable forming rollers to bear against the other wall of the tube, positively rotating the tube about its longitudinal axis, moving the axis of the single roller and pair of rollers towards each other and simultaneously moving two of the rollers along their axis or axes towards the third roller whereby a convolution is formed in one operation in the wall of the tube as said tube is rotated.
 2. A method as claimed in claim 1, wherein the single roller is arranged to bear against the inner wall of the tube and the pair of rollers are arranged to bear against the outer wall of the tube.
 3. The method defined in claim 1, wherein said single roller engages the inner periphery of said tube and said pair of rollers are axially spaced and engage the outer periphery of said tube one at each side of said single roller, said inner roller is displaced axially of the tube toward one of said outer rollers, and the other of said outer rollers is displaced in said direction at a faster rate.
 4. Apparatus for forming convolutions in a tube comprising rotatable means for mounting one end of a tube, said means being rotatable about the longitudinal axis of said tube, a single inner roller mounted on a first axis for peripheral engagement with the inner surface of said tube, two axially spaced outer rollers mounted on a second axis for peripheral engagement with the outer surface of said tube, said inner roller engaging the tube in a region between said outer rollers, and said spindle axes being parallel to the axis of rotation of the tube, and means for moving the inner roller substantially radially outwardly with respect to the rotating tube and axially toward one of said outer rollers while at the same time axially displacing the other of said outer rollers in the same direction.
 5. The apparatus defined in claim 4, wherein said other outer roller is displaced at a faster rate than said inner roller.
 6. The apparatus defined in claim 5 wherein said other outer roller is displaced at substantially twice the rate as said inner roller.
 7. Apparatus as defined in claim 4, wherein said rollers are all mounted for free rotation about their respective axes.
 8. The apparatus defined in claim 4, wherein said outer rollers are mounted on a common spindle, one of said outer rollers being axially slidable on said spindle aNd the other of said outer rollers being fixed on said spindle.
 9. The apparatus defined in claim 8, wherein said spindle is mounted for rotation and axial displacement.
 10. The apparatus defined in claim 9, wherein said spindle is carried by a member that is mounted for displacement axially and radially of said tube.
 11. The apparatus defined in claim 4, wherein said inner roller is mounted on a spindle journaled in a machine post that is movable both radially and axially of said tube.
 12. The apparatus defined in claim 4, wherein said tube mounting means is rotatable about a substantially vertical axis and means is provided thereon for clamping the lower end of said tube to fix the tube coaxially with said axis, the upper end of said tube being axially free. 